Check and unloading valve structure



` Aug.1s,1942.. w, ERNST :2,293,334

HE K AND UNLOADING R original Filed May 5,1939 2 sheets-sheet 1 N- a I LT- Y WALTER ERNsr;

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W. ERNST CHECK ANDUNLOADING VALVE STRUCTURE Aug; la, 1942.

\ l Original Filed Mayl 5, 1939 2 Sheets-Sheet 2 loa N MW, l J. MT

l ............,H.,..........,.nM-MNHN m 2 m Patented Av.ug. l8, 19.42

' CHECK uNrrED- STATES PATrNrOFFI-CE lfaniela/34 I' V d' .u v

Walter Ernst, Mount 'Gileadf'oiim .assignorv to The Hydraulic Development Corp., Inc., Wilmington, Del., va corporation ot Delaware"V74 original application May-5, 1939,- seriai No.

2725011. Divided and this application September ze, .1939, serial N0. 4296,969

This invention relates to *hydraulic machinery, and in particular, to hydraulic press systems.

`One object of thisfinventio'n is to provide a hydraulic press systemv having a"hollow main ra`m with; a booster area in a booster chamber,I

- main ramhas traveled a predetermined variable distance, dependent upon the adjustment of vthe booster ram. 'Y

Another object is to providea hydraulic ress system having a main ram with a main ram area and a booster area within the main ram, and a fluid passageway interconnecting the main ram area with the booster area, thepressure fluid being conveyed tothe booster area vby means of a fixed booster plunger having'a bore therethrough, the head of the fixed plunger being adapted to uncover one end ofthe passageway afterl the main ram has moved a predetermined distance `so thatthe pressure fluid-flows into the booster` ram chamber and then through the passageway to the' main ram chamber so as to apply the full force of the pressure fluid tothe Y entire area of the main ram. x

` Another object is to providea hydraulic press system of 'the type set forth in the preceding objects wherein a single pressure fluid conneci tion suillces for the supplying voi! pressure'uid to both the booster ram area area.` I i Another object is to provide a hydraulic press system having a main plunger with a chamber connected to a combinatloncheck and unloading valve, the'latter being pilot-operated to open automatically when pressure .fluid isj suppliedv to the pilot chamber. Y y f, vAnother object is to provide a combination check and unloading valve in a single casing having a check valve chamber` connected to an unloading valv'e chamber within which` an unloading valve piunger reciprocates, ythis plunger havinga plungerlifting chamber whichis conl but one direction, yet the unloading plunger when i operated by pressure fluid within its pilot chamber permits flow of fluid in the opposite direction wherein vthe ball check valve is closed.

v plurality dt predetermined positions. l

' c claims. (ci. 121-385 plston head-ol the ram,thisxpassageway having a plurality of spaced ports so as to cause by-passing of the fluid and'haltlng of the plunger at one lof a This application is a division of my applicatie .Serial N0. 272,011, filed May 5, 1939.

In the drawings:

, Figure 1 is a diagrammatic view, partlyin secy tion, showing the hydraulic press .systemnf this invention in a preferred embodiment.

` Figure 2 is a fragmentary view of a portion of Figure 1 showing the main ram in its advanced position. A

Figure 3is'a central vertical section through the 4combination vcheck and unloading valve of the invention. y

In general, the hydraulic press system of this Kinvention 'consists'of a main cylinder having a main ramarea and main chamber connected to a combination check and unloading valve, which, in turn, communicate with av fluid reservoir, such .as an oil tank. -The main ram is hollow, being provided with a central chamber into which a stationary piston projects. This stationary pisand the main; ram.. I

ton is hollow and at its outer end is-connected to a source of pressure fluid through suitable conram travels relatively to the head of the sta- 4 tionaryhollow piston. In this manner pressure fluid is first conveyed through the hollow piston to the central or booster chamber of the main ram and after the latter has traveled a predetermined distance this fluid also reaches the main ram area through the passageways.

' chamber isj a separate plunger 'lifting chamber Another'vobject is to provide ahydraulic press' system having a ram within a cylinder,4 together with a by-pass passageway interconnecting the cylinder bore portions on opposite vsides of the Referring to the drawings in detail, Figure 1 to-which pressure fluid may be admitted' to cause the unloading valve plunger to lift, thereby opening communication from the checkvalve chamber through the unloading waive 'chamber to Sa 1 dis/charge conduit. 'I'his discharge conduit mayv lead' to the fluid reservoir such asan oil tank.

shows diagrammatically the hydraulic system of 'the invention as applied to a plastic injection molding press. The press, generally designated I0, is supplied with pressure fluid from a pair of pumps II and I2 driven by a motor I3. The dis.

. tribution of the pressure iiuid from the pumps pressure fluid in the event of the failure of other/ safety devices. The pumps II and I2 are preferably ofthe variable delivery type having a flow control member which is movable to vary the amount of reciprocation of the pistons and accordingly to vary the rate of discharge of the pumps. As is well-known to those skilled in the art, such variable delivery pumps are usually supplied with mechanism for automatically shifting these flow control members to neutral positions when the pressure in a part of the circuit reaches a predetermined maximum. The safety valves I1 and I8 protect the circuit against overpressures in the event `that this so-called pump centering mechanism fails to operate.

The plastic injection molding press to which the invention is applied is shown at the top of Figure 1 and consists of a clamping unit I9, a die cushioning unit 20, and an injection unit 2|. The supporting structures, such as the machine frame, are omitted in order to simplify the showing and illustrate the remaining details more clearly.

The injection unit 2i consists of a cylinder 22 within which a double-acting piston 23 reciprocates. Connected to the piston 23 is a piston rod 24 which for puposes of simplification is shown to constitute an injection plunger which reciprocates in the material injecting chamber 25. The latter has a bore 26 and a nozzle 21, together with a hopper 28 having a passageway 23 communicating with the bore 26: The piston rod 24 is surrounded by a packing 38 adapted to be compressed by a-gland 3| in order to prevent leakage. The opposite ends oi the cylinder 22 are provided with ports 32 and 33 connected by the conduits 34 and 35 to the injection' control valve I4. The latter is provided with an exhaust conduit 38 leading to the'oil tank-31, and likewise with a pressure iiuid inlet conduit 38 connected to the pump -I I. The pump II is provided with a suction conduit 83 opening into the oil tank 31. The

safetyvalve I1. is connected by the conduit 4F55 to the conduit 38 and discharges through the conduit 4I into the tank 31. The injection cylinder 22 is provided with a pair of additional ports 42 and interconnected by the conduit 44 containing the ball check valve 45. This' arrangement serves to halt the retraction of `the 'piston 23 when it passes the port 43 at its rear edge, thereby serving to bypath the discharge of the `pump through the line 44 and check valve 45.

The cushioning unit consists of a substantially stationary die head 48 upon which one of the Vacarrear cushioning purposes. For this reason the die head 46 is mounted upon a plurality of cushioning pistons 48 (one only being shown) these reciprocating in die cushioning cylinder 50. The piston 49 is connected to the die head 46 by means of a piston rod 5I. and a tail rod 52 extends in the opposite direction from the piston 49. The piston rod 5I and tail rod 52 are provided with longitudinal passageways 53 and 54 leading respectively to conduits 55 and 56. These conduits are connected as described below.

The die clamping unit I9 consists of a cylinder 51 within which the main ram 58 reciprocates. On the end .of the main ram 58 is mounted a platen 59 serving to support arid move the movable die or mold (not shown) which cooperates with the stationary die or mold mounted upon the die head 46. The main ram 58 is provided with a head 60 and a piston rod 6I connecting the head with the platen 59. Leakage around the piston rod 6I is prevented by a gland 62 and spaced packngs 63 and 64 separated by a cham- `ber 65.` From the latter the port 66 is connectedA to the drainage conduit 61 leading downward to the tank-31. 1

The piston rod 6I is provided with an internal bore,68, the end` 89 of which forms the so-called booster area of the main ram 58. Opening into Athe bore68 are ports 10 having'passageways 1I to the main ram area I2 on the end of the piston head 60, the opposite end 13 of whichforms the into the oil tank 31. A port conduit 80 leadsl from'the clamping control valve I5 to the port 8| at the rearward end of the main cylinder 51 by way of the connection cap 82". 'I'he port 8i leads into a passageway or chamber 83 surroundingthe piston rod 84. The chamber 83 is closed by an end plate 85. The piston rod 84 carries a piston head 86 fitting smoothly into the bore 88 within the main ram 58. Piston rod 84 and piston head 88 are traversed by an L shaped passageway 81 leading from the chamber 83 to the bore 88 adjacent the booster area 69. The piston rod 84 and piston 88, are held in a stationary position by means of the threaded portion 88 threaded into the threaded bore 88 in the cylinder 51.

vIt will be observed that the conduits 55 and 58 leading from the opposite end of the piston rod 5I and tail rod 52 associated with the cushioning unit 20 are connected respectively to the conduits 80 and 18 leading to the opposite end of the main cylinder 51. The rearwardv end of the main cylinder 51 is provided with a port 38 to which is connected the conduit 8l leading to the combination check and unloading valve I8. From the opposite side of the latter the exhaust con;

molding dies is mounted (not shown). The die head 46 is provided with a socket 41 for receiving the nozzle 21. The socket 41 communicates with a material conveying passageway 48 which leads to the die cavity within the-,mold oridie mountedA upon the die head 48. The die head 48 is relatively stationary but is capable of a limited amount -ot motion for duits 32 and 33 lead intothe oil tank 81. The

- pump I2 is provided with a suction conduit 84 and the safety yvalve I8 with an intake conduit 85 connected to the conduit 18. together with an exhaust conduit 86 which discharges into the tank 31. f

The combination check and unloading valve I8 (Figure 3) consists of a casing 31 having a chama reduced diameter portion and I2.

` operate the press in its various movements.

head 49 escapes through' the conduit 58 to the conduit 18and thence to the exhaustconduit 19 land. the tank 31 by way of the clamping control valve I5. When the desired clamping pressure has lbeen reached, the -ilow c 'ontrol member of the pump I2 automatically shifts to its neutral position. Meanwhile, as the main ram 58 has adtom thereof beneath the ball 99. A side port' |05 l0 leads into an adjacent unloading valve chamber |06 communicating with a vertical bore 01 within which the unloading valve plunger 'I 08 reciprovanced, iuid is drawn into the' rearward end of the main cylinder 51 throughthe pipe9l and past the ball check valve member 99, which is raised by the suction thus created. In this mancates. Abovethe upper end of the bore |01 there is provided. an enlarged coaxial bore |09 serving l5 to receive the pilot head I0 on the valve plunger |08. The latter is surrounded by the annular l plunger lifting Achamber I having a threaded port ||2 to which is connected the conduit I|3 leading to a connection with the conduit 18,and

thereby connected to the retraction circuit forv the main ram 58. Above the-enlarged head |I0 the plunger I08`is provided with a further enlargement 4 reciprocable ,within a spring l I|8 secured to the 25 chamber I5 closed by a cap casing 91 by, the screws |I1. largement ||4 the plunger |08 Beyondv the enis providedjwith l ||8 surrounded by a spring v||9 urging the unloading valve plunger |01 leading into the pipe-93. Consequently when Operation In the operation of the hydraulic press system of this invention the operatorI starts the motor pushes it and the piston rod 24, together with the l linject-ion molding material through the bore 28 |08 downwardly to a position closing the borev 30 pressure fluid is admitted into the pipe |.I3 and I3, thereby plaeingvin operation the pumps 40 Assuming the parts of the' press |0 to be in the retracted positions shown in Figure l, the operator now operates the clamping control valve I5 and the injection VLcontrol valve L4 to To clamp the dies, the operator shifts the valve member |20 of the clamping control valve up. wardly, thereby placing the pressure conduit 02A inv coirnmunication' with the conduit 180. Pressure iluid then flows from the pump |-2 through the conduits 82 and 80 to the port 8|, thence into the chamber 83,and through the piston rod passageway into the end of the'ram chamber 88 adjacent the booster area 89 thereof. As .the

`latter area is of relativelyl small diameter, ther5 main ram 58 and platen 59 move forward at a relatively rapid rate.- Meanwhile, the fluid in front ofthe ram head 50 is discharged `through the port 11, the conduit 18, the valve I5 and the exhaustv conduit 19 into the oil tank 31.

When the main ram 58 has traveled forward to apoint where the Vports 10 are uncovered in passing the stationary 'piston head 86 (Figure. 2) n the pressure uid within the booster chamber v88 escapes through the ports 10 and passageways 1I 65 into the rearward end of the main cylinder 51 to the left of the main ram area 12, The fullpress.- ing force is now exertedupon the platen 59 and i the die or mold'halves areV held firmly together with a very great force. n, 4 r While this is. occurring pressure uid also flows through the conduit 55 into the cushioning cylinder 50 and thereby yieldingly support the die head 48 and the die or moldhalf carried therev ,mjurthe'r travel thereof.

by. The fluid on the opposite sideof thepiston'7 28 and 'suitably heated the -injection ner', fluid passesu upwardly from the oil tank -31 through the pipes 92 and.9| to the main cylinder v51. When pressure 'enters the rearward end of the main cylinder 51, however, as shown in Figure 2, this pressure immediately closes the ball check valve member 99 upon its seat |00, aided To perform an injection stroke after having placed injection molding 4material in the hopper cylinder the operator shifts the-valve member |2| of the injection control valve I4 upwardly, thereby ard- 4 mitting pressure fluid fromthe pump discharge line 38 tothe conduit 34 and thence into the right hand end of. the injection operating cylinder'22.

'This pressure acts against the piston head A23 and and out thejnozzle 21 intothe channel or passageway 48 from whence-it passes into the mold cavity between the mold halves.

To retract the injector, the operator moves-the valve member |2| downward aided by the coil spring |23 so that the flow of pressure uid to .the injector piston 23 is reversed, pressure iluid entering through the conduit l and the displaced iiuid returning to the tank through the conduit 34 and the exhaust conduit 36. When the piston head 23 passes the port 43 in the cylinder 22, fluid thenlows through the conduit 44 and past the check` valve 45 into the right hand t end of the cylinder 22, then through the conduits 34 and 36 into the tank 31, thencefo'rth'by-passing the discharge of the pump .and haltingthe retraction or the pistohead 23.

'To unclamp the dies or mold halves, the operator moves the vvalve member |20 of the clampthrough the conduit ||3 to theplunger lifting chamber I oi' the unloading valve plunger |08,

lifting the latter and opening the check valve. chamber 98 into communication with the exhaust conduit 93.' The fluid displacedv from the lefthand end of the main cylinder 51 thenis per? mitted to pass throughthe conduit I9 into the chamber 98, thencethrough the port |05 (Figure 3) and through the chamber 08, Tnto the exhaust conduit 93. When the piston head arrives at the position shown in Figure 1, it uncoversthe port 15, whereupon the fluid is bye passed around'the piston. head 80, halting the At the same time, the clamping plunger 49 moves backward and ends its cushioning action operation can then be repeated in the same mari-v ner.

'I'he piston rod 84 is provided with suitable means, such as the squared end |30, whereby the The foregoing cycle' of k prises means for the purpose of causing the halting of the piston head 60 at different points on its retraction stroke.' A press of this type frequently employs dies of dilerent thicknesses, depending upon the kind of workpiece to be molded. It is necessary, in designing such a press, to provide for a suilicient retraction of the main ram 58 to enable the use of the thickest dies likely to be encountered in ordinary practice. When thin dies are used, such as for the making oi thin workpieces, valuable time is lost in retracting the main or clamping plunger 58lto a greater distance than is necessary for opening the dies 'I'he arrangement,

and ejecting the workpiece. shown in Figure 1 enables the apparatus to be adjusted so that for thin dies 'the main ram or clamping ram 58 will be retracted ashorter distance than with thick dies.) S ch thin dies are used, for example, in the making -oLcombs or spectacle frames. 9

In addition to the by- 'ass ports 1`4'and 15,

the -by-pass passageway 16 is provided with additional ports |4| and |42 on the retractioniside` of the main ram head 60. These ports 4| and |42 are provided with ,valve seats |43 and |44, containing ball check valves |45 and |46. Opposite the valve seats |43 and 44 are threaded ports |41 and-|48, into which screws |49 and |50 are threaded. By rotating these-screws' to bring their inner ends into engagement with the balls |45 yand |46, the ports |4| and |42 may be positively closed so that the ram head 60 will not halt until it uncovers the port 15. If, however, it

is desired to halt the ram head at an intermediate, port, the screw |49 is rotated in a reverse direction so as to permit the ball |45to lmove. Accordingly, when the ram head 60 uncovers the portV |4| on its retraction stroke, the ball |45 will be forced away from its seat |43, thereby permitting fluid to flow through the port 4| and the by-pass passageway 16, throughthe port 'l4,into the opposite end of the cylinder 51, halting the retraction of the main of clamping 1 ram 58.

If extremely thin dies are to be used, the screw |50 is also rotated to free the ball check valve |46. yAccordinglyywhen the port |42 is uncovered by theram head 60, during the retraction stroke, pressure uid will flow through the fport |42 into the by-pass passageway `||i,after raising `theiball check valve |46 away from its seat |44. Thus, the ram head 60 will halt after a' shorter retractionstroke than if the` port |4| or the port 15 were employed.

' The screws |48 and A|50 may eitherbe solid or may be provided with sockets 5|, with springs ,|52 engaging the ball check valves |45 and |46.

Caps |53 are provided for covering'the ends of l the screws |49 and |50 so as to discourage tampering with the adjustment thereof. Locknuts |54 may also be optionally provided to lock, the

screws |48 and |50 in their adjusted positions.

It will be understood that I desire to comprehend within my invention lsuch modifications as come within the scope of the claims. Having thus fully described my invention, what I claim -as new and fdesire to secure by 5 Letters Patent, is: l

1. A combination check and unloading valve for use in circuit relation with a hydraulic motor comprising a casing having a check valve chamber and an unloading valve chamber, separate passageways respectively leading from said chambers and continuously connected with a fluid 4reser oir for the motor, said check valve chamber b ing continuously connected with the advancing side of the hydraulic motor, conduit means interconnecting said chambers, a unidirectional ow check valve member movable in response to a suction Aeffect in said check valve chamber to open one of said passageways for iiuid flow toward the advancing side o1' the hydraulic motor, and an unloading'valve member continuously urged intoclosing position and having an area in continuous hydraulic communication with the retraction side of said hydraulic motor, said unloading valve member being operable by fluid pressure acting upon said retraction side for moving said unloading valve member into unloading position to open the other of said passageways, thereby by-passingl said check valve.

2. A combination check and unloading valve for use in circuit relation with a hydraulic motor comprising a casing having a check valve chamber and an unloading `valve chamber, separate passageways leading from said chambers and continuous'ly connected with a fluid reservoir for the motor, a port interconnecting said chambers,

conduit means continuously connecting said check valve chamber with the advancing side of ahydraulic motor, a unidirectional flow check 40 valve member monable in response to a suction effect in said check valve chamber to open one of said passageways for fluidow toward the advancing side of the hydraulic motor, anunloading valve member movable to open the other v of said passageways independently of the control of the first mentioned passageway, a hydraulic cylinder associated with said unloading valve chamber and a hydraulic piston associated with said cylinder connected to s aid unloading valve member for moving the same between its closed and open positions, said cylinder having means hydraulically connecting the same with the retraction side of said hydraulic motor for operating said piston. f

3.`A combination checkv and unloading valve comprising a casing having a. check valve chamber and an unloading valve chamber in continuous fluid communication with each other, a ilrst conduit for admitting fluid to said check valve chamber, a second conduit for discharge of fluid from said check valve chamber, a third conduit for discharge of fluid from said unloading valve chamber, a checkivalve member in said check valve chamber arranged for unidirectional flow of fluid through said valve member casing, anI

, unloading valve in said unloading chamber, a separate hydraulic cylinder having a piston therein operatively connected to said unloading .valve member, and conduit meansconveying fluid pressurel to said cylinder to -actuate said piston and open said unloading valve member irrespective of the pressure condition in said valve member, thereby by-passing said check valve member. I

4. A combination check and unloading valve for use in circuit relation with a hydraulic motor comprising `a casing having a check valve chamber and an unloading valve chamber continuously hydraulically connected with each other, a first conduit forI admitting fluid to said check valve chamber, a second conduit for discharge of fluid from* said checkvvalve chamber to the advancing side of the motor, a third conduit iorV discharge of iluid from said 4unloading valve chamber, a` check valve member in said check valve chamber arranged for unidirectional flow of fluid through said valve casing, an unloadingv valve member in said unloading chamber, a separate hydraulic cylinder having a piston therein operatively connected to said unloading valve member, and conduit means for conveying iiuid pressure to said cylinder from the push back side lof the motor vto actuate said piston and open said unloading valve in response to a predetermined fluid pressure acting upon the pushv back side of said motor,irrespective of the fluid pressure prevailing in said check valve der in said body having a piston arranged therein in substantial vcoaxial alignment with said un-.'

loading chamber and operatively connected to said unloading valve, said piston being responsive to a predetermined pressure in said separate cylinder, irrespective of the pressure condition in said unloading valve chamber, and'means for conveying iluid pressure to said cylinder to y actuate said piston to open said unloading valve chamber, thereby by-passing said check valve member.

l5. A combination check and unloading valve comprising a valve body having a check valve chamber and an unloading valve chamber continuously hydraulically connected with each other; a first conduit for admitting iluid to said check valve chamber, a second conduit for dis-V and to by-pass said check valve member.

6. A combination. check and unloading valve comprising a valve body having a check valve chamber and an unloading valve chamber continuously hydraulically connected with each other, a rst conduit' for admitting iluid to said check valvechamber, a second conduit for discharge of iluid from said check valve chamber,

a third conduit for discharge of fluid from lsaid unloading valve chamber, a check valve memberin said check valve chamber arranged for unidirectional flow of fluid through said valve, body,

an unloading valve plunger reclprocable in said unloading chamber for selectively establishing or interrupting hydraulic communication between said unloading valve chamber and said thirdV conduit, resilient means continuously urging said plunger into a position for interrupting said last mentioned hydraulic communication, and iiuid pressure responsive means operatively connected with said plunger and responsive to a predetermined pressure acting upon said iluid pressure ',responsive means irrespective or the pressure condition in said unloading valve chamber for establishing the said hydraulic communication, thereby by`passing said check valve member.

WALTER, ERNST. 

